Dehydration apparatus



Oct. 15, 1935. E, OSKAMP 2,017,728

DEHYDRATION APPARATUS Filed Jan. 251955 -2 sheets-sheet 1 lll l i @MY 7 Oct.'15, 1935. H. E. osKAMP I I DEHYDRATIQN APPARATUS 2 Sheets-Sheet 2 Filed Jan. 25, 1953 Patented oct. 1s, 193s UNITED STATES PATENT oFFlcE lmainz:marron Arranarns Howard E. Oskamp, Wheaton, 111.". Application January 23,1933, serial No. esame 6 Claims.

My invention relates in general to dehydration,

and in particular toapparatus for accomplishing the dehydration.

' Dehydration in the past has been accomplished generally by passing heated air through chambers of various types to remove the moisturev from vegetables'and other food stuffs stacked therein. The drying is carried on while at the same time attempting to retain the `vitamlnand l' mineral content in the food stuis as well as the iiavor, `so that the same food value will be obtained from eating the-concentrated product as' might Ibeobtained from vegtables and the like "in their original form. Dehydrated food stus 15"1 have found considerable use where the facilities for transportation are either limited or so expensive as to necessitate the greatest food value inthe smallest bulk. Dehydrated food stuffs have also found application inthe field of medi- ZQJ-cine, where the medicinal qualities of the food are utilized in concentrated form as amore efiective cure for the ailment under treatment. A great effort has been made in the past to obtain a uniform heated-air distributionin every 35* medicinal qualities and in some instances it ,has often `been impossible to obtain two containers of a dehydrated product in which the desired mineral or vitamin value of the contents is the same.` `This situation has hindered the extent ofthe use 10i-0f dehydrated products.

In anfeiort to. eliminate the so-called hot spotsf veryelaborate and lextensivey dehydrating plants have Abeen built up, which in turn materi- 45 ally increase the cost of thedehydrated product. Th'e means for heating the airinftheselarge ,plants has. in general been n'arrcwved.'downl to' ysteam or hot-water'heat or hot air-furnace. These-means for heating the air, introduce the process, and.termi 1i atethe dehydration at the :provide e an -improved apparatus for dehydration.

5.a A further` object isto provide an apparatus As a' result of this situation the de,

i.;problemof sensitive heat control soy as t 11min,` tain the .required temperature throughout the which accomplishes dehydration in a 'manner insuring the retention of vitamin and mineral content of food stuis dehydrated.

It isa further object to provide an apparatus having a dehydrating chamber in which the heat distribution is uniform in every point of that chamber, resulting ina uniform product.

A further object is to provide'a means for circulating the air through the dehydrating cham- -ber so as to obtain a uniform temperature inl0 every point in the chamber.

A further object is to provide a simple and inexpensive apparatus for dehydratingl 4food stuffs.

It is also an object of my invention to provide air heating means in the complete dehydrating apparatus capable of sensitive temperature control, to prevent scorching and burning.

A still further object isto provide a dehydrating apparatus capable oi being set up in relatively' small complete individual units so as to provide separate units for foods having conicting odors, while at the same'time maintaining' a low initial and operatingccst.l

Other objectsl and advantages of my invention will be apparent from the description taken with the drawings, in which;y

4 Fig. 1 is a sfide view partly in section of the complete dehydrating apparatus.

Fig. 2 is an ehlarged fragmentaryl portion of 30 'the tray support alongthe line 2-2 lof Fig. 1

with food stuffs distributed on the trays-pre-y lin'iinary to dehydration.

Fig. 3 isla front elevation along the line 8 3 35 of Fig. 1, showing the front view of the air diffuser.

Fig. 4 is afront elevation partlyy in -section along the line -Avof Fig. l.

Fig. 5 is a front elevation 'along'the line 5 5 of Fig. l ofthe heating element and fan chamber. I

n ,Fig. 6 is side view in section of the ianand air directing means; with arrows illustrating' the .path of the air circulatedy outwardly from' the l fan, intox the dehydrating chamber;v and Fig., 7 isl a front velevationgof amodication 'oi the4 diiiuser.

lIn practicing invention I' provide an# insu- 'lated .drying chamber having a squared interior, 50

witha framework positioned',-therein for holdy I, o ing drying trays.r A perioratedbttom isf'propropen'time. It 1s anobject of my invention to,`

.vided in thetraysto permit ready circulation. o!

` through the drying chamber.

Referring now to the drawings: An insulating chamber II, as illustrated in Fig. 1, is provided which comprises an outer covering I2,

V which may be of wood, or any other suitable material, and insulating board I3 separated by insulating material I4. This provides a heavy insulated wall, sufficient to maintain the necessary drying temperature in the chamber I6. Access to the drying chamber I6 is provided through the hinged door I1 insulated in the same manner as described for the walls. In dehydrating food stuffs it has been found advisable to slice the vegetables, meat or the like, and lay the slices in trays having perforated bottoms, to allow the ready circulation of air-over the maximum surface made possible by cutting up the food stuffs to be dehydrated. When the :food stuffs are originally put in the trays, the pores are open. The dehydration must be carried out in such a manner that the moisture is evaporated from the material without closing up the pores too quickly or rupturing the cell walls, thus retaining the desired cell contents in their original value. Scorching or burning the material or closing up the pores destroys the food or medicinal qualities desired and when the dehydrated material is later ground up, mixed and packed, the unevenness heretofore discussed, results. A frame I8 is provided for holding the trays 22, which frame comprises suitably supported posts I9 in upright position, with angle bars 2I at spaced intervals on the posts to provide runways for the trays. Any desired number of trays may be used depending upon the available space in the drying chamber. Each tray 22 comprises a frame 23 which may be made of metal, wood or any other suitable material with a coarse-mesh wire cloth bottom 24, secured to the sides in any suitable manner as shown in Fig. 2. Various types of vegetables are shown distributed over the perforated bottom in Fig. 2 to illustrate the manner in which food stuis are distributed over these trays for dehydrating.

Heated air is circulated through the drying chamber I6 by means including a fan 26 mounted in a fan chamber 21, to the rear of the dr'ying chamber I6 and communicating therewith through an opening 28. The fan chamber 21 may 'be constructed of any suitable material, preferably a heavy composition board which will serve as a heat insulator, and a mounting on which electric heating `elements 29 may be secured in each corner. With respect to the heating elements, very satisfactory results have been obtained with an ordinary replaceable unit comprising an earthenware cone 3I having a coil of resistancewire 3,2 wound thereon, and a plug (not shown) secured to one end and connected with the heating coil 32 to be inserted in a socket 33.

The sockets are mounted one in each corner of the ian chamber with suitable connection to a sible to readily replace them in case they burn out with use. The adjustable inlet 34 in the back of the fan chamber, makes it possible to' control the influx of the air which isfdrawn in by the fan and blown into the drying chamber. 5

As discussed above, many of the objectionable consequences of the 'dehydrating processes such as non-uniform product, loss of vitamin and mineral content were the `result of an uneven distribution of the heated air employed in the dry- 10 ing. If the air was blown into the drying chamber by means of a. fan, those portions adjacent the air inlet dried more quickly than those further removed, and the heat adjacent the inlet in order to be great enough to maintain the necessary 15 temperature throughout the drying chamberwas so great often as to burn or scorch the food stuffs. The air diiuser 36 mounted in the opening 28 is designed to eliminate these diillculties and produce an air ilow which is spread out 20 radially from the ifaceof the member in the manner illustrated in Fig. 6.

The diffuser 36 as illustratedin Fig. 3 is circular in form and consists of a series of deilectors 31, which are inclined preferably at an angle of 2| approximately 45 tothe axis of rotation of the fan. The deilectors are spaced apart radially so that the senil-circular horizontally extending plane of the top of one deilector is slightly re' moved from a like plane of the bottom of the $0 defiector immediately above the rst. .'I'his provides passages or slots 38 between adjacent defiectors with the latter forming inclined walls for the slots. The deflectors are preferably arranged in concentric circles with ribs 89 spaced at intervals around the entire diffuser and ex'- tending radially from the center II.` A rim 42 on the outside of the deflectorsiorms the necessary support for the ribs 39. The rim 8.2 'also provides an anchoring flange for retaining the n diiuser in the opening 28. The member may be stamped out of a single piece of sheet metal, with six deilector sections supported by the intervening ribs 38.-

As a result of the operation of the diifuser Il, the direct longitudinally moving air column from the fan 26 is spread out radially into a substantially conical form causing/the moving air to mix and intermingle withthe surrounding relatively still air with a minimum loss of flow. The intero mingling and mixing is promoted by' the deflection and counter-dellection of the air as it strikes the frame I 8 and trays 22, as well as the walls of the dehydrating chamber. It has been found that heat will in a measure cling to the walls of the chamber I 6, and unless circulated will form areas of a higher temperature than the surrounding air. This is overcome in a satisfactory manner as the result of my diffuser causing the individual air columns to emanate from the face thereof at o an angleL of approximatelyv 45. Although the air is deflected in part as it passes through the frame I8 and drying trays 22, sumcient amount strikes the walls of the squared dehydrating chamber I6 to in effect wash" said walls and maintain a a circulation of air throughout the entire chamber. The washing" operation is important in preventing the formation of hot spots" as heretofore discussed, and also promotes the general circulation and distribution orheated air throughout the 70 entire dehydrating chamber.

In operating the dehydrator I have found that the highest efficiency both as to the circulation and distributionof air, and the operation of the fan is obtained by positioning the fan 26 so that ,P

I im.;

. a center portion 82.

the same principles hertofore described. v

the'blades rotate in a plane from t to 1% of inch removed from the circulator 38.

A modification of the diffuser i's illustrated .in Fig. 7 which is substantially square in shape. This `diffuser 16 comprises four. triangular deflector sections made up of individual deflectors 11 formed at an angle of with axis of rotation of the fan similar to deflectors 31 and having passages 18 between planes of adjacent deflectors. Ribs 19 separate the deector sections and `serve as supports for the deectors 11, while the ribs in turn are supported by a rim 8| cooperating with The air is projected from diffuser 16 substantially in the form of an inverted pyramid/to circulate the air' uniformly over the entire dehydrating chamber. It is also understood that other geometrical forms may be used for the diffuser, with each construction employing Means for' recirculating a portion of the heated airis provided by the upwardlyextending duct 43 with an opening 40 as illustrated inkFig. vl, which duct connects with 4a rearwardly extending e passage 44 supported in the roof ofthe chamber I l, and insulated on the upper and lower sides in the same manner as the outside walls of the chamber. 'Ihis passage connects with. a downwardly extending portion 46 vwhich in turn opens into the fan' chamber 21. The air recirculated is that which has passed through the drying chamber without becoming saturated and naturally risesto the top .to be drawn oif through the port 4B. Recirculating the heated air in this manner reduces the amount of heating necessary on the fresh air drawn in through the inlet 34 in order to. maintain the same drying temperature.

An outlet 41 is provided adjacent the iloor in one corner of the chamber I6and provides means for removing the saturated or partially saturated air from the drying chamber I6. Inasmuch as this saturated air is heavier than normal, it readily sinks to the bottom of. the chamber in the circulating processfand is carried through the pipe 48 to the outside of the room in which the dehydrator Il is mounted. A damper 49 permits adiustment of this opening as it becomes necessary to vary the amount of 'air to be blown out of chamber I6. `I have found it advisable to malntain a slight pressure within the drying chamber, and obtain this by maintaining the effective area of outlet 41 smaller than vthe area of inlet 34, preferably in the ratio of 4 to 5.

In practicing the invention, the vegetables, fruits, or other articles to be dehydrated are first sliced and then thoroughly washed. While wet the articles are placed on the trays 2,2 and the latter slid into position on the frame i8. The frame I8, which is square in its outside dimensions, to correspond to the squared drying chamber I8.v is slidably placed in the chamber through the door to a position in which an open space of perhaps 6 inches is maintained around all sides and toll and bottom as shown in Fig.. 1. This spacing facilitates the air circulation throughout the chamber an'd aids in maintaining a uniform heat, distribution. After sealing thechamber i6; the heating elements 29' are turnedon and the fan 2B simultaneously started This immediately starts the circulation of heated airthrough the chamber I6, which air is recirculated in part, with the remaining saturated or partially saturated portion discharged through the pipe 48 tothe outside.

Any suitable thermostat may be employed for regulating the temperature in the drying chamber, and this connected with the electric heating from which the air is drawn 4through inlet 34 so as to determine the length ottime over which the drying must be continued.v However, drying is. not completed 'abruptly and no harm results from 1o continuing the circulation of heated air through the chamber after this pointv is reached, and labrupt termination isI not necessary. The processmay be continued without detrimental effects inasmuch as the temperature in the chamber I6 is 15 maintained below the danger point by thermostatic control, and the uniform distribution of air u throughout the chamber prevents theA formation of hot points".

After the dehydration is completed the trays 22 2o....

may bere'moved from the drying chamber l 6 and the' dehydrated products ground up ortreated in any desired manner.

By the use of my method.' I therefore dehydrate vegetables. fruits and other-` food stuifs at a low. 25.

controlled temperature in a mannerto vproduce a uniform product retaining all the` desired inin-i eral and vitamin content, as well as the original iiavor. The apparatus employed is simple and inexpensive to construct, and makes'possible a uni- 8'0 form heated air distribution throughout the drying chamber which prevents the undesirable consequences heretofore discussed. u

The simple construction of .the dehydrator makes itpossible to construct and maintain a 35 l battery of individual units so thatA food stuil's having 'coniiicting odors may be separately. treated to prevent any mixingwhatever.

Although I have described my process and apparatus in its preferred embodiment, it is under- 0i stood that variations may be made therein without departing from the spirit y'and scope of the invention, and I limit my invention only by the scope of the appended claims.

What I claim as new and desire to protect by 4.5`

Letters Patent of the United States is:

1. An vapparatus for dehydrating foodstuffs and the like comprising only a single dehydrating chamber having a squared interior, means for supporting', foodstuifs in spaced relationship in 50` said chamber, a fan mounted at one wall of the chamber in the center thereof, means for heating the air to be supplied to the fan, air diffusing means mounted directly infront of the fan for directin'gf the air from the: fan forwardly 'b5-A and outwardly therefrom'in an inverted Icone shape, said air diffusing means including aplurality 'of connected deector segments with the outside faces in a single vertical plane and positioned in` a manner to present pairs of segments extending from thercenter' ofthe said means o utwardly in opposite directions, with each deflector segment comprising a plurality of spaced apart concentric de'fiectors extending inwardly from f the face thereof and toward the center of said 05 diifus'lng means, whereby to provide a uniform heated\ air distribution and'circulation to the entiresquared chamber, 'andan air outlet adjacent the bottom of the .chamber providing forl the passage of air therefrom. l u

v2. An apparatus forv 1i hydrating lfoodstuil's and the like comprising a sngledehydrating chamber having fourjwalls and atop and a bottom, means for supporting foodstuffs in spaced relationship in said chamber, a fan mounted at 15 t having air diffusing means mounted directly in front of said fan to distribute air uniformly throughout said chamber, said air diffusing means comprising a one-piece member having a plurality of deflector segments, with one segment comprising a plurality of concentric deflector blades extending from the face of the member inwardly and upwardly, and an adjacent segment having deflectors extending inwardly and sidewardly, means for recirculating a portion of the air from the chamber, said means including an air shaft comparatively small in cross-section opening directly out of the chamber at the wall opposite the fan mounting wall at the top of said chamber and extending rearwardly and downwardly outside thereof to the fan, and an air outlet in the fan mounting wall of the chamber beneath said fan for Are- `rearwardly moving the heavy moisture-laden air from said chamber.

3. An apparatus for dehydrating foodstuis and the like comprising only a single substantially closed dehydrating chamber having front and rear walls, side walls and a top and bottom, means for supporting foodstuffs, in spaced relationship in said chamber, with said rear wall apertured at the center thereof, afan mounted in back of said wall directly to the rear of said aperture, air diffusing means mounted in'said aperture in front of said fan to distribute air uniformly throughout said chamber, said air diffusing means comprising a one-piece member having a plurality of deflector segments, with one segment comprising a plurality of concentric deector blades extending from the face of the member inwardly and upwardly, and an adjacent segment having deflectors extending inwardly and sidewardly, an air shaft opening out of the top front of said chamber and extending and downwardly on the outside thereof to the fan for recirculating a portion of the air from the chamber, and an outlet opening ,out of the rear wall of the chamber beneath the fan for removing the remaining portion of the air in the chamber, which said portion is heavily moisture laden.

4. An apparatus for dehydrating foodstuffs and the like comprising a single dehydrating chamber having a squared interior, means for supporting foodstuffs in said chamber with said chamber having a rear wall apertured in the center thereof, a fan mounted to the rear of said aperture, an air diffuser supported in the aperture directly in front of the fan including a plurality `of supported deflectors lying in a single vertical plane and arranged in parallel concentric form from the center of said diffuser with each deiector extending inwardly at an angle of 45 with a line perpendicular to the center of 2,017,728 i one wallkof the chamber in the center thereof said diuser whereby to direct air from the fan forwardly and outwardly therefrom in a substantial inverted coneA shape to provide uniform air distribution throughout the squared chamber and to strike'the walls thereof in a washe 5 ing action, an air shaft opening out of the top front of said chamber for recirculating a portion of the air and an outlet at the rear bottom of the chamber for escape of the remaining portion.

5. In an apparatus for dehydrating foodstuffs and the like, a dehydrating chamber having a squared interior for receiving foodstus in spaced relationship, with said interior having substantially closed walls on top, on the bot- 15 tom, and all sides, with the rear wall apertured in the center thereof for carrying an air diffuser, a fan housing with an opening in the back f of the same supported outside the rear wall and communicating with the interior through the 20 aperture in the rear wall, air heating means in the housing, a fan mounted in said housing directly in back of the aperture in the squared interior for drawing air through the opening to be heated in the housing, and impelling the heated 25 air through the diffuser to be distributed evenly throughout the squared interior, with said top of the interior having an opening in the front and center thereof, and a duct leading therefrom over said topto open into the top of the fan 30 housing whereby a portion of the heated moisture laden air is directed through said duct to the fan housing to mix with the fresh air and be reheated as a new mixture for recirculation by the diffuser throughout the squared interior and 35 over all Walls thereof and an outlet' to permit free passage of air'from said chamber.

6. An apparatus for dehydrating foodstuffs and the like comprising a single dehydrating chamber having four walls, a top and a bottom, 40 means for supporting material to be dehydrated in spaced relationship in said chamber, a fan mounted at one wall of the chamber having air diffusing means mounted directly in front of said fan to distribute air throughout said cham- 45 ber, said air diffusing means including a plurality of connected deflector segments with the outside faces in a single vertical plane and positioned in a manner to present pairs of segments extending yfrom the center of the said 50 means outwardly in opposite directions, with each defl'ector segment comprising a plurality of ldeectors spaced substantially equally apart over their length extending inwardly from the face thereof and toward the axis, of the fan, a 55 shaft opening out of the chamber for carrying air for recirculation to the chamber, and an air outlet adjacent the bottom of the chamber for removing moisture-laden air therefrom.

HOWARD E. OSKAMP. 

